// ==========================================================
// Bitmap conversion routines
//
// Design and implementation by
// - Riley McNiff (rmcniff@marexgroup.com)
//
// This file is part of FreeImage 3
//
// COVERED CODE IS PROVIDED UNDER THIS LICENSE ON AN "AS IS" BASIS, WITHOUT WARRANTY
// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTIES
// THAT THE COVERED CODE IS FREE OF DEFECTS, MERCHANTABLE, FIT FOR A PARTICULAR PURPOSE
// OR NON-INFRINGING. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE COVERED
// CODE IS WITH YOU. SHOULD ANY COVERED CODE PROVE DEFECTIVE IN ANY RESPECT, YOU (NOT
// THE INITIAL DEVELOPER OR ANY OTHER CONTRIBUTOR) ASSUME THE COST OF ANY NECESSARY
// SERVICING, REPAIR OR CORRECTION. THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL
// PART OF THIS LICENSE. NO USE OF ANY COVERED CODE IS AUTHORIZED HEREUNDER EXCEPT UNDER
// THIS DISCLAIMER.
//
// Use at your own risk!
// ==========================================================

#include "FreeImage.h"
#include "Utilities.h"

// ----------------------------------------------------------
//  internal conversions X to 4 bits
// ----------------------------------------------------------

void DLL_CALLCONV
FreeImage_ConvertLine1To4(BYTE *target, BYTE *source, int width_in_pixels) {
    BOOL hinibble = TRUE;
    for (int cols = 0; cols < width_in_pixels; cols++){
        if (hinibble == TRUE){
            target[cols >> 1] = ((source[cols >> 3] & (0x80 >> (cols & 0x07))) != 0 ? 15 : 0) << 4;
        }
        else {
            target[cols >> 1] |= ((source[cols >> 3] & (0x80 >> (cols & 0x07))) != 0 ? 15 : 0);
        }

        hinibble = !hinibble;
    }
}

void DLL_CALLCONV
FreeImage_ConvertLine8To4(BYTE *target, BYTE *source, int width_in_pixels, RGBQUAD *palette) {
    BOOL hinibble = TRUE;
    BYTE index;

    for (int cols = 0; cols < width_in_pixels; cols++){
        index = GREY(palette[source[cols]].rgbRed, palette[source[cols]].rgbGreen, palette[source[cols]].rgbBlue);
        if (hinibble) {
            target[cols >> 1] = (index & 0xF0);
        } else {
            target[cols >> 1] |= (index >> 4);
        }

        hinibble = !hinibble;
    }
}

void DLL_CALLCONV
FreeImage_ConvertLine16To4_555(BYTE *target, BYTE *source, int width_in_pixels) {
    WORD *bits = (WORD *)source;
    BOOL hinibble = TRUE;

    for (int cols = 0; cols < width_in_pixels; cols++) {
        if (hinibble) {
            target[cols >> 1] = GREY((((bits[cols] & FI16_555_RED_MASK) >> FI16_555_RED_SHIFT) * 0xFF) / 0x1F,
                                     (((bits[cols] & FI16_555_GREEN_MASK) >> FI16_555_GREEN_SHIFT) * 0xFF) / 0x1F,
                                     (((bits[cols] & FI16_555_BLUE_MASK) >> FI16_555_BLUE_SHIFT) * 0xFF) / 0x1F)
                                & 0xF0;
        } else {
            target[cols >> 1] |= GREY((((bits[cols] & FI16_555_RED_MASK) >> FI16_555_RED_SHIFT) * 0xFF) / 0x1F,
                                      (((bits[cols] & FI16_555_GREEN_MASK) >> FI16_555_GREEN_SHIFT) * 0xFF) / 0x1F,
                                      (((bits[cols] & FI16_555_BLUE_MASK) >> FI16_555_BLUE_SHIFT) * 0xFF) / 0x1F)
                                 >> 4;
        }

        hinibble = !hinibble;
    }
}

void DLL_CALLCONV
FreeImage_ConvertLine16To4_565(BYTE *target, BYTE *source, int width_in_pixels) {
    WORD *bits = (WORD *)source;
    BOOL hinibble = TRUE;

    for (int cols = 0; cols < width_in_pixels; cols++) {
        if (hinibble) {
            target[cols >> 1] = GREY((((bits[cols] & FI16_565_RED_MASK) >> FI16_565_RED_SHIFT) * 0xFF) / 0x1F,
                                     (((bits[cols] & FI16_565_GREEN_MASK) >> FI16_565_GREEN_SHIFT) * 0xFF) / 0x3F,
                                     (((bits[cols] & FI16_565_BLUE_MASK) >> FI16_565_BLUE_SHIFT) * 0xFF) / 0x1F)
                                & 0xF0;
        } else {
            target[cols >> 1] |= GREY((((bits[cols] & FI16_565_RED_MASK) >> FI16_565_RED_SHIFT) * 0xFF) / 0x1F,
                                      (((bits[cols] & FI16_565_GREEN_MASK) >> FI16_565_GREEN_SHIFT) * 0xFF) / 0x3F,
                                      (((bits[cols] & FI16_565_BLUE_MASK) >> FI16_565_BLUE_SHIFT) * 0xFF) / 0x1F)
                                 >> 4;
        }

        hinibble = !hinibble;
    }
}

void DLL_CALLCONV
FreeImage_ConvertLine24To4(BYTE *target, BYTE *source, int width_in_pixels) {
    BOOL hinibble = TRUE;

    for (int cols = 0; cols < width_in_pixels; cols++) {
        if (hinibble) {
            target[cols >> 1] = GREY(source[FI_RGBA_RED], source[FI_RGBA_GREEN], source[FI_RGBA_BLUE]) & 0xF0;
        } else {
            target[cols >> 1] |= GREY(source[FI_RGBA_RED], source[FI_RGBA_GREEN], source[FI_RGBA_BLUE]) >> 4;
        }

        source += 3;
        hinibble = !hinibble;
    }
}

void DLL_CALLCONV
FreeImage_ConvertLine32To4(BYTE *target, BYTE *source, int width_in_pixels) {
    BOOL hinibble = TRUE;

    for (int cols = 0; cols < width_in_pixels; cols++) {
        if (hinibble) {
            target[cols >> 1] = GREY(source[FI_RGBA_RED], source[FI_RGBA_GREEN], source[FI_RGBA_BLUE]) & 0xF0;
        } else {
            target[cols >> 1] |= GREY(source[FI_RGBA_RED], source[FI_RGBA_GREEN], source[FI_RGBA_BLUE]) >> 4;
        }

        source += 4;
        hinibble = !hinibble;
    }
}

// ----------------------------------------------------------
//   smart convert X to 4 bits
// ----------------------------------------------------------

FIBITMAP * DLL_CALLCONV
FreeImage_ConvertTo4Bits(FIBITMAP *dib) {
    if(!FreeImage_HasPixels(dib)) return NULL;

    const int bpp = FreeImage_GetBPP(dib);

    if(bpp != 4) {
        const int width  = FreeImage_GetWidth(dib);
        const int height = FreeImage_GetHeight(dib);
        FIBITMAP *new_dib = FreeImage_Allocate(width, height, 4);

        if(new_dib == NULL) {
            return NULL;
        }

        // copy metadata from src to dst
        FreeImage_CloneMetadata(new_dib, dib);

        // Build a greyscale palette (*always* needed for image processing)

        RGBQUAD *new_pal = FreeImage_GetPalette(new_dib);

        for(int i = 0; i < 16; i++) {
            new_pal[i].rgbRed   = (BYTE)((i << 4) + i);
            new_pal[i].rgbGreen = (BYTE)((i << 4) + i);
            new_pal[i].rgbBlue  = (BYTE)((i << 4) + i);
        }

        switch(bpp) {
            case 1:
                {
                    if(FreeImage_GetColorType(dib) == FIC_PALETTE) {

                        // Copy the palette

                        RGBQUAD *old_pal = FreeImage_GetPalette(dib);
                        memcpy(&new_pal[0], &old_pal[0], sizeof(RGBQUAD));
                        memcpy(&new_pal[15], &old_pal[1], sizeof(RGBQUAD));

                    }
                    else if(FreeImage_GetColorType(dib) == FIC_MINISWHITE) {

                        // Reverse the grayscale palette

                        for(int i = 0; i < 16; i++) {
                            new_pal[i].rgbRed = new_pal[i].rgbGreen = new_pal[i].rgbBlue = (BYTE)(255 - ((i << 4) + i));
                        }
                    }

                    // Expand and copy the bitmap data

                    for (int rows = 0; rows < height; rows++) {
                        FreeImage_ConvertLine1To4(FreeImage_GetScanLine(new_dib, rows), FreeImage_GetScanLine(dib, rows), width);
                    }
                    return new_dib;
                }

            case 8 :
                {
                    // Expand and copy the bitmap data

                    for (int rows = 0; rows < height; rows++) {
                        FreeImage_ConvertLine8To4(FreeImage_GetScanLine(new_dib, rows), FreeImage_GetScanLine(dib, rows), width, FreeImage_GetPalette(dib));
                    }
                    return new_dib;
                }

            case 16 :
                {
                    // Expand and copy the bitmap data

                    for (int rows = 0; rows < height; rows++) {
                        if ((FreeImage_GetRedMask(dib) == FI16_565_RED_MASK) && (FreeImage_GetGreenMask(dib) == FI16_565_GREEN_MASK) && (FreeImage_GetBlueMask(dib) == FI16_565_BLUE_MASK)) {
                            FreeImage_ConvertLine16To4_565(FreeImage_GetScanLine(new_dib, rows), FreeImage_GetScanLine(dib, rows), width);
                        } else {
                            FreeImage_ConvertLine16To4_555(FreeImage_GetScanLine(new_dib, rows), FreeImage_GetScanLine(dib, rows), width);
                        }
                    }

                    return new_dib;
                }

            case 24 :
                {
                    // Expand and copy the bitmap data

                    for (int rows = 0; rows < height; rows++) {
                        FreeImage_ConvertLine24To4(FreeImage_GetScanLine(new_dib, rows), FreeImage_GetScanLine(dib, rows), width);
                    }
                    return new_dib;
                }

            case 32 :
                {
                    // Expand and copy the bitmap data

                    for (int rows = 0; rows < height; rows++) {
                        FreeImage_ConvertLine32To4(FreeImage_GetScanLine(new_dib, rows), FreeImage_GetScanLine(dib, rows), width);
                    }
                    return new_dib;
                }
        }
    }

    return FreeImage_Clone(dib);
}
